1. Field of the Invention
The present invention relates generally to fireplace furnaces adapted for insertion within existing conventional fireplaces and more particularly to a combination fireplace furnace and cookstove.
2. Description of the Prior Art
Conventional fireplaces are notoriously inefficient room heaters because they draw warm room air into the fireplace and up the chimney when used. This problem can be solved by use of doors on the fireplace, but their use substantially reduces the radiation of heat from a fire in the fireplace into the room.
To improve the efficiency of such fireplaces, several approaches have been taken. Fireplace furnaces of the "heatalator" type are well known, in which the fireplace itself is built with special heat outlet openings in the front wall of the fireplace above or alongside the fireplace opening so that air can be circulated along side and rear heat exchanging surfaces of the firebox and heated for discharge into the room through such openings. However, these designs all require either rebuilding or modification of an existing fireplace or installation of the furnace during the original construction of the fireplace.
To provide a more efficient fireplace furnace, I designed a self-contained prefabricated fireplace furnace for insertion within a conventional fireplace, shown in my U.S. Pat. No. 4,015,581, issued Apr. 5, 1977. The heater unit includes a metal firebox within a surrounding metal jacket. Room air is drawn into side inlet openings at the front of the jacket, warmed by the firebox walls serving as heat exchange surfaces, and then expelled back into the room through an upper portion of the jacket, all by natural convection. Although this heater is satisfactory to maintain warm temperatures in a room, it requires a considerable length of time to heat a cold room because of the low rate of air movement through the heater.
Use of fans to provide forced air circulation through fireplace heaters has been previously proposed in U.S. Pat. Nos. 2,642,859 and 2,743,720. However, use of such fans does not entirely solve the problem because of their tendency to move air though the heater and back into the room before the air could be adequately warmed because of the limited heat exchange surface area in the heater.
I therefore devised a further improved fireplace furnace as disclosed in my U.S. Pat. No. 4,166,444. Such furnace has a jacketed firebox with heat exchange tubes extending through the firebox from the airspace at the rear of the firebox to discharge openings at the front of the firebox. This design enables efficient use of the heat produced by a fire by circulating room air first through the side and rear airspace and then through the heat exchange tubes, thereby exposing such air to progressively hotter portions of the firebox chamber.
Although my foregoing improved design provides optimum efficiency in a fireplace furnace, it and all other known fireplace furnaces have two disadvantages when compared to conventional free-standing woodstoves, namely, (1) they cannot be used for cooking, and (2) they do not radiate heat as effectively as a woodstove.
Therefore, a primary object of the present invention is to provide a fireplace furnace having all of the advantages of my prior fireplace furnaces, and, in addition, the advantages of a woodstove; namely, the ability to cook and radiate heat effectively.
Another primary object of the present invention is to provide a combination fireplace furnace and cookstove adapted for insertion as a unit into the front opening of an existing fireplace.